Effects of Induced Hypoprolactinemia on Testicular Function during Gonadal Maturation in the Rat

Abstract

We have evaluated the effects of hypoprolactinemia during gonadal maturation in the male rat. Intact 30-day-old rats were injected daily for 10 days with three different doses of bromocriptine (0.75, 1.5 or 3.0 mg/kg of body weight/day). At the end of the treatment period, the animals were sacrificed, serum was collected for prolactin (PRL), LH, and androgen measurements. Intratesticular testosterone and 5 alpha-androstanediol (androstanediol) were measured following celite column chromatography and a specific radioimmunoassay. In addition, the production of androgens by decapsulated testes and dispersed Leydig cells was also studied in vitro. Serum levels of PRL (9.4 +/- 1.9 ng/ml) were suppressed to undetectable levels in the three bromocriptine-treated groups, whereas LH levels were not altered. All three doses of bromocriptine markedly depressed serum testosterone (plus DHT) and androstanediol. Intra-testicular testosterone and androstanediol were diminished (25% and 35%, respectively, P less than 0.05) during hypoprolactinemia. Decapsulated testes and dispersed Leydig cells from bromocriptine-treated animals showed a significant reduction in the basal secretion of testosterone (plus DHT) and androstanediol, and in androgen responses to submaximal hCG stimulation. Maximal steroidogenic responses from bromocriptine-treated rats were similar to controls. The present findings show that, during puberty, bromocriptine influences testicular steroidogenesis, and these effects may be partly due to changes in PRL levels. A direct effect of this dopaminergic agonist on the male gonad cannot be completely ruled out.

Modulatory Effects of Leptin on Leydig Cell Function of Normal and Hyperleptinemic Rats

“…The within- and inter-assay CVs were less than 8 and 13%, respectively, for both RIAs [17]. Testosterone (T) levels in serum, tissue and incubation medium were measured by RIA using testosterone [1,2– 3 H (N), 60 Ci/mmol] from New England Nuclear (Boston, Mass., USA) and a specific antibody from Immunotech Diagnostic (Montreal, Canada), as previously described and validated [18]. Androstandiol was evaluated by RIA using 5α-androstane-3α,17β-diol-1,2– 3 H (SA 40.9 Ci/mmol) and a highly specific antibody (5α-androstane-3α,17β-diol-15-CMO-HAS) from Immunotech Diagnostic.…”

Serotonin in Golden Hamster Testes: Testicular Levels, Immunolocalization and Role during Sexual Development and Photoperiodic Regression-Recrudescence Transition

“…Determination of testosterone in incubation medium was carried out by RIA without extraction by the method previously described by Suescun et al [40]and validated by Frungieri et al [11, 26]. Testosterone was measured using the antibody testosterone-7α-butyrate-BSA, which is known to have 35% cross-reactivity with dihydrotestosterone (DHT).…”

Testicular Interstitial Cells as Targets for Peripheral Benzodiazepines

“…Testosterone concentration in media from cellular incubations were assayed by radioimmunoassay (RIA) as previously described [27], There was no cross-reactivity in the RIA when samples of med ium-containing 10-9-l()-4 M Ro 5-4864, PK 11195, clonazepam and diazepam were incubated in a manner identical to that of incu bation media [data not shown). …”

“…On the day of the experiment the animals were killed by deca pitation and the testes quickly removed. The crude interstitial cell fraction was obtained by collagenase dispersion as previously des cribed [27]. Under these conditions cell viability exceeded 95% and about 20-25% stained for 3-|l-hydroxysteroid dehydrogenase [16].…”